Structural characterization of tripodal phosphine complexes of transition metals. Examples of chair and twisted-boat conformations in six-membered chelate rings

Article abstract of DOI:10.1016/0022-328X(90)87302-T

Complexation of a hybrid tripodal ligand 2,2-bis(diphenylphosphinomethyl)-1-methoxypropane (P2O) with group VI carbonyls, nickel(II) and palladium(II) compounds has been studied.Thus P2O reacts with M(CO)6, NiCl2 and PdCl2 to give (P2O)M(CO)4 (M = Cr, Mo, W), (P2O)NiCl2 and P2O)PdCl2, respectively.All the complexes have been characterized by spectroscopy and elemental analysis, and the crystal structures of the complexes of (P2O)Mo(CO)4 (4b), (P2O)W(CO)4 (4c) and (P2O)NiCl2 (6) have been determined by X-ray diffraction.In all cases, the tripodal ligand behaves solely as a bidentate with phosphorus coordinating to the metal centers.In the examination of the conformations of the six-membered chelate rings, it was found that both 4b and 4c were in the twisted-boat form; whereas 6 was in the chair form.The possible reasons for this conformational difference are discussed.